Slight yellowing on edge of leaf?

[spuddzrmeandyou]

Is this anything to be concerned about? My 5 seedlings are 12 days since germination, currently under CFLs (abt 1 inch from the light). They seem to be doing okay to my uneducated eye, but I noticed today one of them was starting to show some slight discoloration along one of the edges of the first set of leaves. Does this indicate some problem, or am I being too paranoid. Ph is right at 7 according to my el cheapo meter. Using FF ocean forest soil and no nutes, just water. I am careful to just water them when they really need it. My humidity is low though as it is super dry here... I am able to get the humidty to about 38-40% but thats it until I can buy some sort of humidifier. Would the low humidity cause this?

 

[Alistair]

FFOF soil is what is known as a hot soil; it contains lots of nitrogen. It might be a bit of nitrogen burn. If your pH is good and you're not fertilizing yet, in my opinion you've nothing to worry about. Wait until someone else jumps in and see what they have to say.

 

[spuddzrmeandyou]

The yellowing/brown spots are increasing, some of the lower leaves are now completely brown. HELP!

These pix are 19 days since sprouting
Planted in soil, FF Ocean Forest with some perlite
Ph is about 6.8
I have not starting any nutes yet.
Temps are staying around mid to upper 70's, Humidity is at 50% at the moment.
I have been careful not to overwater, I wait until the soil is dry and the plant starts drooping before I water (some of these i just watered last night so they are a little droopy)

Alistair, is it still nothing to worry about? Or are the plants eating themselves and its time to start fertilizing them? Or something else more insidious? Thanks for any advice!!! I don't want to add nutes only to make the problem worse!